1. Filed of the Invention
The present invention relates to a double-sided image reading apparatus and to an image forming apparatus, such as an image copying apparatus, a facsimile machine, or a composite apparatus combining the above, utilizing the double-sided image reading apparatus.
2. Related Background Art
Conventionally, an apparatus for reading images recorded on both sides of an original document has been proposed, and in Japanese Unexamined Patent Publication Showa No. 60-126964 (first prior art), for example, a structure with two image reading means opposing each other for reading simultaneously double sides of an original document by one-time feeding of the original document is suggested.
Also in Japanese Unexamined Patent Heisei No. 1-126870 (second prior art), a structure having two image reading means opposing each other which sandwich an original document pressing roller for reading respectively each side of an original document by switching back the original document is suggested.
In the above-described first prior art, however, the two image reading means require two image processing means, thereby increasing the production cost. In addition, when an apparatus for one-sided reading as a standard configuration which optionally has a double-sided reading function is to be developed, the standard configuration having a one-sided reading function still requires two image processing means for the optional double-sided reading function cost advantage provided by an apparatus having only a one-sided reading function.
Also, in the above-described second prior art, an original document returned by switching back is to be read from the rear end of the sheet, which causes the image information to be sent upside down, page by page, when, for example, the information is sent as FAX images. In order to avoid this situation, a means for reversing the up or down side of an image or a conveying means for reversing the up or down side of an image is required, thus making the apparatus structure complicated.
Furthermore, in the conventional original document conveying route of the image reading apparatus, especially an original document conveying route having a U-turn section for sequentially feeding by a plurality of original document conveying means, when a part of the original document conveying means conveys original documents at a slow speed, the speed as a whole for processing the original documents becomes slow; or when a preceding original document conveying means is fast while a following original document conveying means is slow, the original document conveying means does not fit in the original document conveying route, hindering the image reading means from reading images precisely.
Therefore, it is an object of the present invention to provide an image reading apparatus and an image forming apparatus which are excellent without defects, and more specifically to achieve miniaturization and cost lowering of an image reading apparatus and an image forming apparatus mounting the image reading apparatus.
Also it is an object of the present invention to provide an image reading apparatus and an image forming apparatus capable of reading good images while improving an operating efficiency of the reading process of the original documents by differentiating the conveying speeds between the original document conveying means.
To accomplish the above objects, a representative structure of a double-sided image reading apparatus according to the invention is to structure an original document conveying route, an original document conveying means for conveying an original document along the original document conveying route, a first reading means for reading an image on one side of the original document, and a second reading means for reading an image on the other side of the original document, where an image on one side of an original document is read at the first reading means while the original document is forwardly conveyed by the original document conveying means and then after being conveyed in a reverse direction, the other side of the original document is read at the second reading means while being conveyed forward again.
According to the above-mentioned image reading apparatus, the image information on both sides of the original document can be read one by one as well as in the same direction with respect to the up side and the down side of the original document, which allows feeding the original document data to a single image processing means, there is no need for providing a plurality of the image processing means, and, therefore, it is possible to simplify the circuit and miniaturize the base board, thereby reducing cost.
As another structure of the invention, the image reading apparatus of the same as the mentioned above can form a branching conveying route branching off from the original document conveying route at an upstream side, in the conveying direction, of at least one of the image reading means, the branching conveying route capable of guiding the original document conveyed by the original document conveying means.
Because the above-mentioned image reading apparatus has, in addition to the original document conveying route, another branching conveying route for making the original document conveyed in the reverse direction temporarily escape, the original document can escape smoothly even if the original document conveying route has a U-turn shape.
As another structure of the invention, the image reading apparatus might include an original document conveying route having at least a partial curvature section having a U-turn shaped portion and a reverse path branching off from a midway point on the original document conveying route, the reverse path having at least a partial curvature section having a U-turn shaped portion.
According to the above-mentioned image reading apparatus, when conveyed in a reverse direction for escape, the original document is returned on an original document mounting tray serving as an original document feeding means, thereby making an apparatus installation space smaller.
As another structure of the invention, an image reading apparatus includes an original document feeding means for feeding stacked original documents, an original document conveying route for conveying the original documents fed from the original document feeding means, at least one image forming means placed in a midway point on the original document conveying route, and a plurality of original document conveying means for conveying the original documents in the original document conveying route, each of the original document conveying means having a document conveying speed different from that of at least one adjacent original document conveying means.
In the above-mentioned image reading apparatus, an original document processing efficiency can be improved as a whole in the original document conveying route and also a degree of tension and a degree of flexion of the original documents can be controlled between the plurality of original document conveying means. Therefore the image reading means can read good images.